The membrane, M, protein of influenza virus has been cleaved with cyanogen bromide and the fragments separated, one of which consists of 71% hydrophobic amino acids. The fragments will be sequenced and their order determined. The data will be used to determine structural aspects of the virus and for comparative studies on M from other strains of virus. The nonstructural, NS, component is made in large amounts in the cell and is found in soluble, uncomplexed form and as large insoluble crystalline masses. Studies on the structure of NS will be carried out; these studies will also determine if soluble NS is modified in some way which may pertain to its biological function. Studies with ts mutants will involve isolation of NS mutants, re-investigation of our NS-, M- mutants and standardization of our ts mutants with those of others. Recombination will be studied by analyzing mutant, recombinant and wild-type proteins in two dimensions, the first by charge (isoelectric focusing) and the second by size (SDS gels). Studies on the non-plaque former will be continued.